1. Field of the Invention
The invention is directed to an air handling system to control the volume of air flowing through an air treatment system in a heating, ventilating and air conditioning system. More particularly, the air handling system of the present invention selectively varies the volume of air which flows through an air treatment system so that when climatic conditions dictate that it is not necessary to cool, heat, humidify or dehumidify all of the volume of incoming air a portion of the incoming air is diverted to a bypass section to pass untreated to the building.
2. Background of the Invention
In conditioning air for larger commercial buildings such as office building, hotels, apartment building and other commercial establishments, it is often unnecessary due to ambient climatic conditions to treat all of the incoming air before distribution through the building. These air treatment systems known as heating, ventilating and air conditioning (HVAC) systems are used to cool incoming air in summer months, heat incoming air in winter months and, depending upon the ambient humidity level of the air to be treated, either humidify or dehumidify the air before ultimate distribution in the building.
Accordingly, most modern HVAC systems have provisions to bypass a volume of incoming air so that the volume of bypassed air is untreated in the cooling, heating humidifying or dehumidifying system. This is sensible and desirable from an economic standpoint as ambient air conditions may dictate that it is unnecessary to treat the total volume of air distributed in a building. On hot humid days a greater volume, if not the total volume of incoming air, is cooled and dehumidified. On the other hand, on a cooler less humid summer day the ambient air may be sufficiently cool and dry so as to be directly distributed within a building without requiring cooling or dehumidification. Similar conditions may exist in winter months on warmer days. Ambient air conditions may also dictate that it is unnecessary to treat the total volume of incoming air but only a portion of the incoming air volume so that part of the air is passed through the HVAC treating system and part of the air volume is directed to bypass the HVAC treatment system to be mixed with the volume of treated air before ultimate distribution throughout the building.
The HVAC industry has recognized the benefit of air bypass systems and has sought to accommodate air bypass systems in various ways, including various types of movable gates, diverter plates or vanes, and dampers and also by limiting the volume of incoming fresh ambient air by recirculation of a portion of the already conditioned and treated air rather than exhausting it to the outside. Such solutions while attempting to address the problem have not been entirely successful and have not succeeded in completely solving problems inherent in such prior systems.
Problems exist in adequate proportioning of conditioned and bypass air due to differences in pressure drops between air moving through a conditioner and air moving through an air bypass system. Problems also exist in bypass systems which use pivoting dampers or vanes because the change in air volumes is not a linear relationship to the movement of the dampers or vanes making control schemes difficult. Further, these systems can never truly seal the flow of air between the air bypass passage and the air passage through the conditioning portion of the system. Thus, leakage of air occurs between the bypass passages and the conditioning passages so that precise control of the volume of air to be conditioned and the volume of air to be bypassed is not feasibly possible.
Accordingly there presently exists a need for an improved conditioned/air bypass system to provide improved and enhanced operation to maximize the benefits of commercial HVAC systems which operate by regulating the volume of air to be conditioned based on the characteristics of outside ambient air at the time the HVAC system is conditioning air for the interior of a building.